Creola bodies (CrBs) have been shown to be present specifically in the sputum of adults with asthma, and are clinically useful in the estimation of airway hyper-responsiveness through correlation with the levels of eosinophil cationic protein in the sputum. Our aim was to investigate whether CrBs can be detected in the sputum of wheezing infants, and the clinical significance of CrBs in wheezing infants in the development of asthma. Twenty-three wheezing infant patients, mean age 5.3 months, were studied. The presence of CrBs in the sputum was determined by Papanicolau's stain. The patients were divided into two groups: CrB positive [CrB(+)] and CrB negative [CrB(-)]. In addition, we examined the relationship between the presence of CrBs and the asthma symptom scores that occurred during a 1-month post-discharge period. The following results were obtained: (i) CrBs were detected in 15 of 23 (65%) wheezing infants; (ii) the asthma symptom scores after discharge was significantly higher in the CrB(+) group than in the CrB(-) group (p < 0.001); (iii) in the infants experiencing their first episode of wheezing, the asthma symptom scores during the post-discharge period was also significantly higher in the CrB(+) group than in the CrB(-) group (p < 0.05). Furthermore, infantile asthma was diagnosed in 12 (80.0%) infants in the CrB(+) group during the following 2-yr period, but none in the CrB(-) group. These findings suggest that CrBs detected in the sputum of wheezing infants may be used to identify the progression to infantile asthma.